<div style="height: 100%; display: flex; flex-direction: column;">
    <div style="margin-bottom: 4px;">
        <button onclick="start()">► Start</button>
        <button onclick="stop()">■ Stop</button>
    </div>
    <div style="flex-grow: 1;">
        <div id="myGrid" style="height: 100%;" class="ag-theme-quartz">
        </div>
    </div>
</div>